Apparatus permitting the measurement of the aerodynamic parameters of a flow by means of a streamlined body orienting itself freely within the said flow and carrying total and static pressure pick-offs.
In the known apparatus of this type, such as those described in French Pat. Nos. 2 113 746 and 2 399 027, provision is made for mounting the pressure pick-off probe on a vane mounted on the cardan joint in such a way that, the probe remaining oriented within the flow, the perturbing influences due to variations in the angle of incidence are theoretically eliminated. In practice, the inertia of the vane and the resisting couples due to the articulated joints cause a situation in which the orientation of the probe is always to a greater or lesser extent displaced in relation to the sense of the flow. The result of this is that the measurement of the local angle of incidence .alpha., and by deduction that of the aircraft carrying the probe, which is obtained by a mechanical measurement, is not sufficiently accurate in relation to the characteristics of modern aircraft.